High-pressure fuel pumps are often used for fuel injection systems for internal combustion engines. They exert high pressure on a fuel to be supplied to a combustion chamber of the internal combustion engine and are mostly constructed as piston pumps. In such pumps, a pump piston compresses the fuel located in a pressure chamber by means of a translational back and forth movement and consequently produces a high pressure in the fuel. For example, with high-pressure fuel pumps for petrol internal combustion engines, the fuel is acted on with a pressure of from 200 bar-300 bar whilst the fuel for diesel internal combustion engines is acted on with a pressure of from 2000 bar-3000 bar.
As a result of the high pressures, it is advantageous from a tribological viewpoint to provide a wear-resistant configuration of a piston guide in which the pump piston is guided. To this end, for example, it is known to use a specially constructed guiding sleeve for the pump piston. Such a high-pressure fuel pump is known, for example, from DE 103 22 603 B4.
A positive-locking connection is achieved therein between a guiding sleeve for the pump piston and a housing of the high-pressure fuel pump by pressing in the guiding sleeve and caulking a collar to the housing.
However, this type of positive-locking connection involves high necessary assembly forces of several kN and produces tensions in the components, which may lead to deformations of these components. In this instance, deformations, for example, of valve seats of the high-pressure fuel pump or the guide of the pump piston itself are considered to be particularly critical since they can lead to internal leakage paths and consequently in the worst case to loss of the function of the high-pressure fuel pump.
In addition, during operation of the high-pressure fuel pump, as a result of the operating conditions such as temperature, oscillations, etcetera, a settling behavior of the positive-locking connection may take place at the caulking of the guiding sleeve and a leakage path from a pressure chamber of the high-pressure fuel pump via the outer diameter of the guiding sleeve may thereby occur again since the required pretensioning of the guiding sleeve at the side which is directed toward the pressure chamber is no longer ensured.